Banca de QUALIFICAÇÃO: LAISA DO ROSARIO SOUZA CARNEIRO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LAISA DO ROSARIO SOUZA CARNEIRO
DATE: 08/10/2021
TIME: 09:00
LOCAL: https://conferenciaweb.rnp.br/webconf/peter-ludvig
TITLE:

Hybrid sílica synthesized by sol-gel method as addition or coating for cement pastes

KEY WORDS:

hybrid sol-gel silica; nanostructured silica; superhydrophobicity; hydrophobicity; sol-gel process; pozzolanic activity; durability; mechanical properties

PAGES: 80
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

The issues concerning the durability of buildings are usually related to the presence of humidity or to water infiltration in the porous cementitious materials used in concrete structures. Advances in biomimetics and nanotechnology have allowed the development of superhydrophobic materials, with contact angles greater than 150º, which are able to repel water and aqueous products. The synthesis of such materials generally includes combining a low surface energy material, e.g. alkylsilanes, siloxanes, etc., with a nanostructured one. This study proposes the use of the sol-gel process to synthesize nanostructured hybrid silica, functionalized by organic precursors. Such precursors are either silanes or siloxanes that present a hydrophobic organic branch in its chain, which turns the resulting silica water repelling. Besides, such silicas might present pozzolanic activity when in contact with the cementitious medium. Hence, cementitious coatings and additions will be fabricated from hybrid sol-gel silica, whose properties will be evaluated by mechanical and transport tests in modified cement pastes. The pastes hydrophobicity will be evaluated by water contact angle measurements. The silicas pozzolanicity will be evaluated by electrical conductivity measurements. It is expected that hybrid sol-gel silicas present high pozzolanic activity; and that coated cement pastes and those with hybrid silica incorporated present some hydrophobicity, i. e. water contact angles higher than 90º. It is also expected that both mechanical and transport properties of modified cement pastes are enhanced; and that hybrid silica reacts with Ca(OH)₂, forming hydrophobic C-S-H; and, finally, that cement pastes coated at different ages present different properties.

BANKING MEMBERS:
Presidente - PETER LUDVIG
Interno - CONRADO DE SOUZA RODRIGUES
Externo à Instituição - PHILIPPE JEAN PAUL GLEIZE - UFSC
Externo à Instituição - MANUEL HOUMARD - UFMG